2,6-di-tert-butyl-4-nonylphenol

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

Deviations:

not specified

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Direct dispersion in water
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): not reported

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: The sample was maintained at 21°C with continuous aeration and used on the day of collection
- Name and location of sewage treatment plant where inoculum was collected: Severn Trent Water PLC Sewage Treatment Plant Belper. Debyshire
- Preparation of inoculum for exposure: The pH of the sample was 7.0 and the suspended soils equal 3.9 g/L prior to use

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

3 h

Nominal and measured concentrations:

blank control, positive control, and nominal 1000 mg/L

Details on test conditions:

TEST SYSTEM
- Aeration: yes
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 2
- Sludge concentration (weight of dry solids per volume): 3.9 g/L


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
TEST CONCENTRATIONS
- Spacing factor for test concentrations: limit test
- Justification for using fewer concentrations than requested by guideline: limit test
- Range finding study
- Test concentrations: 100 and 1000 mg/L, no adverse effects observed

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

- Effect concentrations exceeding solubility of substance in test medium: yes
- Blank controls oxygen uptake rate: 0.71 and 0.66 mg O2/L/min
- Coefficient of variation of oxygen uptake rate in control replicates: 4%

Validity criteria fulfilled:

yes

Conclusions:

EC50 > 1000 mg/L

Executive summary:

In the activated sludge respiration inhibition study from Mead (1995) with Isonox 232, the EC50 for respiration inhibition was determined in a limit test to be > 1000 mg/L. Doseverification analysis was not performed. The study is considered reliable with restrictions for the risk assessment.

Description of key information

EC50 > 1000 mg/L

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L

Additional information

In the activated sludge respiration inhibition study from Mead (1995) with Isonox 232, the EC50 for respiration inhibition was determined in a limit test to be > 1000 mg/L. Doseverification analysis was not performed. The study is considered reliable with restrictions for the risk assessment.